In many vehicle powertrain applications it is desirable to engage a clutch pack as a result of inputting an electrical signal to an electromagnetic coil. The clutch pack may control torque between an input and an output. One design of a conventional electromagnetic clutch assembly consists of a friction clutch pack having a plurality of interleaved friction plates, a solenoid coil, an armature plate, and a ball ramp mechanism. In this type of electromagnetic clutch assembly, electrical current is applied to the solenoid coil, which generates a magnetic force that attracts the armature plate to the coil housing and causes the coil housing, armature plate, and one element of the ball ramp mechanism to rotate relative to a second element. Since the second element of the ball ramp mechanism is linked to the output side of the clutch pack, the ball ramp mechanism imparts a clamping force against the clutch pack, thereby, engaging the interleaved friction plates.
Several of the engineering parameters considered when designing an electromagnetic clutch include power consumption, the time necessary to engage/disengage the clutch, the magnitude of the torque transferred, and the ability to modulate torque transfer. It is desirable in the automotive industry to continually improve upon the design of an electromagnetic clutch assembly in order to lower manufacturing costs by either increasing the ease associated with manufacturing each component or by having fewer components to assemble. Accordingly, there exists a need in the industry to continually provide electromagnetic clutch assemblies that are economical to manufacture and to assemble.